1. Field of the Invention
The present invention relates to an electric contact pin, and in particular, to a press-fit contact pin which is inserted into a through hole of a printed substrate (circuit board) and secured thereto.
2. Description of the Prior Art
Conventional press-fit contact pins are disclosed for example, in Japanese Patent Publication No. 58-41633 and in Japanese patent application no. 59-54120 (unexamined).
In this field of art, the diameter of through holes formed in a printed circuit board substrate is very small due to a high density of parts on the substrate. If a conventional press-fit contact pin is scaled down with the shape thereof maintained as it is, the cross-sectional area of the contact pin becomes very small, and accordingly, it becomes difficult for the contact pin to be applied with even the minimum load required for assuring a good electrical and mechanical contact when the pin is inserted into the through hole.
The above-mentioned through hole is usually plated with copper or the like, and it can not be avoided to allow some amount of tolerance of the through hole diameter in fabrication. Therefore, the contact pin is desired to maintain a pressing load above the above-mentioned minimum load even in case various fabricational deviations are caused. Especially, at the present time when the diameter of the through holes have become very small and the influence of the tolerance deviation is relatively great, it is strongly desired that a wide range of the fabricational deviation can be permitted for assuring a good contact.